This invention relates to photography, and particularly to a novel compact imbibition chamber for cameras.
Photographic processes in which the processing of the finished print is commenced as soon as the exposure has been made have been highly developed and take various forms. The processes include those in which the photosensitive materials must be protected from light during the processing procedure, as well as those in which an opacifying composition is employed so that the exposed film unit may be passed through processing rolls and then immediately ejected into a lighted environment without interfering with the process. Typical of latter processes of this type are those involved in the preparation and processing of SX-70 Land film units, made and sold by Polaroid Corporation of Cambridge, Mass.
For some purposes, it is desirable to limit the amount of opacifying composition included in a photographic processing fluid, such as the fluid used in the SX-70 film units. When such limited amounts of opacifier are used, it is necessary to keep the print in a light-protected environment until the processing is well advanced. In order to keep the size of a camera in which the film is exposed and processed to an acceptably compact size, it is undesirable to include an imbibition chamber in the camera. The difficulty is that the film cannot be pulled around a short radius, so that the length of the chamber would have to be added to the length of the film unit. One solution to this problem which has been proposed is to provide a temporary imbibition shield in the form of a plate having light protecting edges at its sides to be used in combination with a film unit having an opaque layer on one side and with a light-sensitive layer ejected into shielded relationship with an opacification device so that it can be left in a light-protected environment, although outside of the camera, for any desired length of time. In order to reduce the size of the camera, the plate is hinged to the camera so that it can be folded back against the camera body when not in use. Such apparatus is shown and described in U.S. Pat. No. 3,369,470, issued on Feb. 20, 1968 to Rogers B. Downey for Camera Apparatus and assigned to the assignee of this application. More restricted light protecting properties have been made available in the form of a self-retracting temporary light shield of the kind shown and described in U.S. Pat. No. 3,938,167, issued on Feb 10, 1976 to J. N. Amey and A. S. Ivester for Film Catcher, and in U.S. Pat. No. 3,940,774, issued on Feb. 24, 1976 to A. S. Ivester for Opaque Shade, both assigned to the assignee of this application. In this apparatus, a coiled, relatively opaque carbon-filled Mylar tab is provided. A film unit just passing through the processing rolls of the camera is ejected into the curl of the coiled tab in such a manner that it is protected by the curled material as it is uncurled until it leaves the processing rolls, at which time it comes out of engagement with the temporary protecting tab and comes into position for removal by the user of the camera. Such apparatus is extremely convenient in use. And the additional dark imbibition time provided is not paid for at the expense of much additional camera complexity or material, because the device is selfretracting into a tight coil immediately after use and thus does not take up much space in the camera.
The object of this invention is to attain the advantages of a longer dark imbibition period while achieving the compactness available with the tightly coiled construction of the above-cited U.S. Pat. Nos. 3,938,167 and 3,940,774.
Briefly, the above and other objects of the invention are attained by a novel imbibition chamber construction in which a film receiving imbibition chamber is provided in the form of a tightly coiled helix of springy opaque sheet material which has been formed with fluted side flanges that will hold the film unit with its photosensitive face in contact with the face of the opaque sheet. The structure is initially tightly coiled into a compact configuration, but is readily extended into a relatively flat configuration by encounter with the film unit.
The process of making an imbibition chamber in accordance with the invention, and the apparatus and its mode of operation, will best be understood in the light of the following detailed description, together with the accompanying drawings, of preferred embodiments of the invention.